Pump assembly



F. E. SMITH PUMP ASSEMBLY Nov. 24, 1953 2 Sheets-Sheet 1 Filed June 21, 1951 Frederic/r E 5272/27? 1%,

HZ Z' EF F. E. SMITH PUMP ASSEMBLY Nov. 24, 1953 2 Sheets-Sheet 2 Filed June 21, 1951 3 4 5 fi xm 6 I 05 A +1 4 W H F v 8 W Z A. Z

a W w ITFE' TTZZLIYT Frederick E. Smith Patented Nov. 24, 1953 PUMP ASSEMBLY Frederick E. Smith, Cleveland Heights, Ohio, as-

signor to Thompson Products, Inc., Cleveland, Ohio, a corporation of Ohio Application June 21, 1951, Serial No. 232,753

13 Claims. (Cl. 244135) This invention relates generally to multiple pump constructions and more particularly to a double aircraft fuel booster pump adapted for submerged operation in an aircraft fuel cell and including pumps on both ends of an electric motor with vapor separating centrifugal impellers driven by the motor and each having a suction inlet at a diflerent level in the fuel cell with the upper inlet controlled by a valve normally closed to unload the impeller associated therewith when the aircraft is operating under normal flight conditions and automatically opened in response to abnormalities in flight conditions to automatically expose the impeller to fuel.

Multiple unit pumps have been provided heretofore with separated inlets adapted to provide. a supply of fuel for at least one of the pumping units during all conditions of flight, for example, during negative gravity flight conditions as well as during positive gravity flight. A particularly useful type of pumping apparatus employed in this connection has utilized a pair of pumping units driven by a common drive motor, each of the pumping units having a separate inlet at a different level of a fuel cell in Which the pumping unit is customarily located.

When both of the separate inlets are open and submerged in fuel, a serious loading problem. is presented because of the extra load placed on the common drive motor.

This problem has been successfully overcome according to the principles of the present invention by providing a valve in one of the pump inlets to isolate one of the impellers during conditions of normal flight when both of the inlets are likely to be concurrently submerged. Suitable actuatin means are provided for the valve to open the valve Whenever abnormalities in flight conditions arise and it is necessary to rel load the isolated impeller for pumping.

More particularly, the present invention contemplates the provision of an inlet valve normally biased open by a control spring and actuated to a closed position by a pressure-sensitive diaphragm referenced to the discharge pressure of the pumping unit. A check valve referenced to a point of lower pressure, for example, the fuel cell, is connected in operative relationship with "the pressure sensitive diaphragm. During norflight conditions, the discharge pressure of the pump actuates the pressure-sensitive diaphragm, thereby rendering the control spring inoperative and closing the inlet valve. The 'check valve is sensitive to gravity and will open 2 under inverted or negative gravity flight conditions to relieve pressure on the diaphragm element and thereby permit the spring to open the valve and expose the pump inlet to the fuel for reloading the impeller.

It is an object of the present invention, therefore, to minimize loading of a multiple unit pump.

Another object of the present invention is to provide a multiple unit pump for an aircraft fuel system wherein one of the pumps will be substantially unloaded during conditions of normal flight.

Yet another object of the present invention is to provide a pumpingunit for an aircraft fuel system having a plurality of pumps driven by a common motor wherein a separate inlet is provided for each pump, one of the inlets being selectively opened and closed in response to changes in flight conditions.

Many other features, advantages and additional objects of the present invention will become manifest to those versed in the art upon making reference to the detailed description which follows and the accompanying sheets of drawings in which a preferred structural embodiment of a pump assembly incorporating the principles of the present invention is shown by way of illustrative example.

On the drawings:

Figure 1 is a fragmentary cross sectional view with parts shown in elevation and with parts broken away showing a pump assembly provided in accordance with the principles of the present invention mounted in the fuel cell of an aircraft;

Figure 2 is an end elevational view of the pump assembly shown in Figure 1;

. Figure 3 is a fragmentary cross sectional view taken substantially on line III-III of Figure 2; and

Figure 4 is a fragmentary cross sectional view with parts shown in elevation showing the upper end of the pump assembly of Figure 1 in invertedposition and with the inlet valve provided in accordance with the principles of the present invention open. As shown on the drawings:

The pumping assemblv of the present invention is indicated generally by the reference numeral l0 and is shown mounted to the bottom wall H of a fuel cell l2 conventionally provided to supply quantities of volatile fuel to the fuel system of an aircraft. A pump cover I3 is mounted onone side of the bottom wall II, a retainer ring 14 abutting the other side of the bottom wall H and receiving a plurality of screws l6 serving to clamp the pumping assembly In in firm assembly with the fuel cell l2 so as to normally be aligned in a predetermined horizontal reference plane when the aircraft with which the fuel cell 12 is associated enjoys normal con ditions of flight.

The pump assembly I comprises a first pump l1 and a second pump l8 each having rotary impellers driven by common drive motor 19. The components of the pump assembly 10 are arranged in coaxial vertically spaced alignment, the motor I9 having a first shaft projecting into a housing 2| providing a volute chamber 2 2 in which a rotar impeller 23 connectedto the shaft 20 is arranged to rotate and a second shaft 24 projecting into a housing 26 providing "a volute chamber 21 in which a second rotary impeller 28 connected to the shaft 24 is arranged to rotate.

It maybe noted that the housing 26 is provided with an extending portion 29 which engages the housing 2! thereby to encase the motor 19 which is held in assembly with the housing 2| by means of suitable fasteners 30. V

The shaft 20 is journaled for rotation relative to the housing 2| by means 6f a bearing assembly indicated at 3| and a seal is established between the housing 2! and the shaft 20 by means or a sealing mechanism indicated at 32. In Figure l the sealing mechanism between the shaft 24 and the housing 26 is indiea'ted at 313. I

Each of thepumps I and I3 is provided with a separate inlet, the pump l'l being provided with an inlet '34 "formed in an annular ring 36 arranged adjacent the end or the impeller 23.

anemia of the pump I8 comprises an annular member forming a valve seat 3'! surrounding an inlet passage 38 adapted to be controlled by a valve 39. v

Because of the orientation "or the pump assembl To in the fuel gen 12, it will be appreciated that the valve seat 31 is aligned in a normally horizontal .plane when the pump assembly I0 is positioned uprightly during normal flight conditions and the valve '39 is arranged to move between an open and a closed position along an axis extending through the inlet passageway 38 and normal to the plane of the valve seat 31. Thus, when the pump assembly I'll is in upright position during normal flight, the weight of the valve 39 will tend to carry same into seating engagement with the valve seat 3'! to close the inlet passageway 38.

By locating the inlet opening 34 and the inlet passageway 38 at opposite ends of the pump assembly, the respective inlets oi the pumps IT and I8 will take suction at 'difierent levels of the fuel cell 12 to insure submergence of at least one of the inlets under negative as well as positive gravity flight conditions.

. Fuel entering the inlet opening '34 will be pressurized by the impeller 23 and discharged from the volute chamber 22 through a discharge opening 40 and into an outlet 4! which is commen to both of the pumps l1 and I8.

Fuel entering the inlet passageway 38 is pressurized by the impeller 28 and is discharged from the volute chamber 21 through the outlet passageway 42 into the common outlet 4|.

Under normal flight conditions, the inlets for both of the pumps H and I il will normally be submerged thereby providing for a full flow of inlet fluid to each of the impellers 23 and 28. y

In order to preclude the possibility of overloading the common drive motor [9 under such operating conditions, the present invention contemplates the isolation of the upper impeller 28 during normal flight conditions thereby afiording a very substantial reduction in motor load. To assist in the isolation of the upper impeller 28, a check valve 46 biased by a coil spring 41 is provided to control the discharge opening 42 leading to the common outlet 4!.

To insure seating of the valve 39 on the valve seat 31, a flexible diaphragm 48 is clamped between an annular peripherally apertured flange portion 49 concentrically arranged relative to the valve seat 3'! and a cap member 50 which is retained in firm assembly with the housing 26 by means of plurality of cap screws 5]. There is provided between the diaphragm 48 and the cap member 50, therefore, a control pressure chamber 52 which may be referenced to the discharge pressure of the fluid delivered to the common outlet 4| by means of a passage 53 and a second passage "55. A screen '43 is clamped around the 'flange portion '49 to prevent entering 61" ore gn inatter into the inlet passageway 38.

The diaphragm 48 iseiampea in firm assembly with the valve 39 by means of a clamp retainer 54 "fastened to the valve 39 by a plurality "of rivets 55. I a

A control s'pring '5! taking the form of a resnient coil spring "seated between the valv seat 3'] and the flange portion 49 engages thevalve t9 and exerts a control bias against the valve 39 in a dii c'ti'on away from the valve seat 31.

To -selectively bleed off pressure from the pressure control chamber 52 to a point of lower pressure such as that existing in the fuel cell [2, a check valve is provided, the structural details of which are clearly shown in Figures 2 and '3. A housing boss "58 is provided with a bore 59 havingan outlet passage 60 communicating with the fuel 'eeu and'ah inlet passageway 6| controlled by a poppet 82 having a conical portion 63 arranged to open and close a seat portion 64 formed inthe inlet passageway 61.

The bore 59 is closed by a cover 86 retained in assembly withthe boss 58 by a pair of screws Bl. Thepoppe't 62 is of a shorter dimension than the length of the bore 59 and is freely reciprocable in the bore '59 so as to control the inlet passage Bl in response to changes in gravimetric force exerted thereupon. I A communicating passageway 68 extends through the boss 53 and intersects the passage 53, thereby to establish communication with the pressure control'chamber 52. l 7

During normal flight conditions when the ump assembly It is positioned uprightly, the poppet 52 engages the seat 64 to close the inlet passage 6! whereupon discharge pressure at the common outlet 4: will be transmitted through thepassage'fiii, the passage 53 and into the press re control chamber 52 to act against the diap'li'r'agm '48. The diaphragm 48 moving in response to the increased pressurization in the pressure control chamber 52 will renderthe conti ol sp'ridn'g 51 inoperative and will move the valve 39 into seating engagement with the valve seat 31, thereby to close off the inlet passageway 38. The impeller 28 of the pump l8 being isolated by closure of the inlet passageway 38, a very substantial reduction in motor load will occur during normal flight conditions even though the inlets of both of the pumps I? and I8 are submerged.

During an abnormal flight condition, for example, if the aircraft is subjected to an inverted flight condition so that the pump assembly I0 is tilted away from its normal plane of reference, the poppet 62 will fall away from the seat 64 and the pressure in the pressure control chamber 52 will be reduced because the fluid transmitted thereto will be bled through the communicating passageway 68, through the inlet passageway 6|, past the seat 64 and outwardly into the fuel cell [2 through the outlet passageway 60. As soon as the diaphragm 48 is unloaded, the control spring 51 again operates to urge the valve 39 away from the valve seat 31, thereby opening the inlet passageway 38 and automatically reloading the impeller 23. The position of the valve 39, the diaphragm 48 and the control spring 51 during an inverted flight position is clearly shown in Figure 4 wherein the control spring 51 has actuated the valve elements to a full open position.

It should be noted that the second passage 55 is provided with a restriction 65 so that pressure can be removed from chamber 52 almost in-- stantly as soon as an abnormal flight condition occurs and the poppet 6-2 falls away from the seat 64. The inlet passage 6|, of course, is provided to embody a sufficiently large capacity to exploit the advantageous provision of the restriction 65, whereby the valve 39 will open rapidly and will afford prompt reloading of th impeller 28 whenever required during the course of airflight.

A screen 15 is also provided in the second passage 55 to prevent clogging of the restriction 65 by foreign material.

Although variou minor structural modifications might be suggested by those versed in the art, it should be clearly understood that I wish to embody within the scope of this patent all such modifications as reasonably and properly come within the scope of my contribution to the art.

I claim as my invention:

1. An aircraft fuel system, comprising, a fuel cell for volatile fuel, a pumping unit including a plurality of impellers and a common drive motor for said impellers, said pumping unit having a common outlet and a separate inlet for each of said impellers, said pumping unit arranged in said fuel cell with each of said inlets at a different level so that a lower inlet will be submerged under normal flight conditions, a valve in an upper inlet, a pressure loaded control means operably connected to said valve to selectively close said valve, passageway means between said outlet and said pressure loaded control means bleeding discharge pressure to said pressure loaded control means to close said valve and unload the impeller of the valved pumping unit, and additional control means engaging said pressure loaded control means to inactivate said pressure loaded control means in response to abnormal flight conditions whereby said valve may open to reload the impeller with fuel.

2. A fuel system for the prime mover of an aircraft, comprising, a fuel cell to contain volatile fuel, a pumping unit including a plurality of impellers and a common drive motor for said impellers, said pumping unit having a common outlet and a separate inlet for each of said impellers, said pumping unit arranged in said fuel cell with each of said inlets aligned on a difierent level so that a lower inlet will be submerged under normal flight conditions, an inlet valve in an upper inlet, a spring exerting an opening bias against said inlet valve, a pressure sensitive diaphragm connected to said valve, casing means providing a pressure control chamber behind said diaphragm to pressure load said diaphragm, a

flow passage from the discharge of said pumping unit to said pressure control chamber, a relief passage from said pressure control chamber to the cell, and a gravity responsive check valve in said relief passage, the discharge of said pumping unit normally pressur loading said inlet valve closed to unload the impeller associated with said upper inlet, said gravity responsive check valve being displaceable in response to abnormalities in flight conditions, thereby to relieve the pressure on said valve, whereupon said spring will urge said inlet valve open.

3. A pumping unit adapted to be mounted in th fuel cell of an aircraft and including a, pluralit of impeller equipped pumps, a common drive motor for said impeller equipped pumps, each of said pumps having a separate inlet, said inlets being spaced apart from one another and. adapted to be arranged at different levels in the cell, a common outlet for said pumps, a valve in one of said inlets and controlling the flow of inlet fluid through said one of said pump inlets, and actuating means engaging said valve and selectively closing said valve during normal flight conditions only to unload the pump associated with said one inlet whenever flight conditions are normal.

4. A pumping unit adapted to be mounted in the fuel cell of an aircraft and including a plurality of impeller equipped pumps, a common drive motor for said impeller equipped pumps, each of said pumps having a separate inlet, said inlets being spaced apart from one another and adapted to be arranged at different levels in the cell, a common outlet for said pumps, and a valve in one of said inlets, biasing means engaging said valve and tending to close said valve in said inlet for unloading one of the pumps, and actuating means engaging said valve and actuating said valve against said biasing means to an open position in response to abnormalities in flight conditions, wherein not all of said separate inlets are submerged, thereby to automatically reload said one of said pumps.

5. A pumping unit adapted to be submerged in the fuel cell of an aircraft and having at least two impellers and a common drive motor to rotate said impellers, said pumping unit having a common outlet for both of said impellers and a separate inlet for each impeller, a valve seat in one of said inlets, and a valve in said inlet closing said seat for unloading one of said impellers during normal flight, said valve seat aligned in a normally horizontal plane when said pumping unit is positioned uprightly, said valve arranged to move along an axis normal to the plane of said valve seat and vertically disposed when said pumping unit is positioned uprightly in normal level flight, gravity bias acting on said valve along said axis tending to move said valve to an open position when said pumping unit is inverted in abnormal flight to automatically reload said one impeller during abnormal flight.

6. A pumping unit normally aligned on a predetermined plane of reference comprising at least two pumps, each pump having a rotary impeller, a common drive motor to actuate said impellers, a common outlet for both of said pumps, a separate inlet for each of said pumps, one of said inlets having a valve seat, a valve in said inlet selectively closing said seat, and an actuating means engaging said valve to move said valve befween an ripeness afclo'sed position, said a ctoatiagneaiaiiiensm position-sensitive means to more said valve into open position whenever spidfiiiiihpih'g unit is 'uiteaaway from said plane cf're'fer'en c'e.

'7. A 'isum iiig'umt normally alignedon a predetermined plane or reference comprising, at rive pumps, each pump having a rotary jinpeur, "a common drive motor to actuate said essences, a common outlet for both of said -iniiif o's,"a 'se'parateinlet for each of said pumps, Queer said inlets having a valve seat, an inlet valve selectively closing said seat, control means exerting an opeh'm bias against said inlet valve, a pressure loadedmea'ns engaging said inlet valve and renames rendering said control means inensure for closing said valve, flow passage terrain said outlet to said pressure loaded sure to's'aid pressure loaded means, and a relief verv connected to said pressure loaded means and to selectively render said pressure loaded ifieaiis'inoprative whereupon said control means will open said inlet valve, said relief valve incorati'ng a position sensing operating element :whereupon said inlet'valve'will be opened to load the aipener'assbciatea therewith only when said in'g unit is tilted out of said Plane of ref trance.

8. An aircraft fuel system comprising a pumpifn'g 'u'nit having a plurality o'ipumps, a common drivingfmotor for said pumps, a separate inlet "fc'r "each pump in spaced apart relation to one aiiaeonmumeaan pump discharge presanother to take suction at different relative levels,

a valve in one of said inlets, means normally erosmgsam valve in said one or said inlets whenever said pumpin unit is positioned uprightly during ncrmal flight conditions and means openi'hg said valve in said one of said inlets 'whenever said pumping unitis tilted towards inverted posi" tion during abnormal flight conditions. m

An aircraft fuel system, comprising, a pumpi'ng can having a plurality of pumpsa common driving motor for said pumps, a separate inlet for each pump in sp ac'ed apart relation to one another to take suction at different relative levels, a poppet valve bias towards 'pen position and being one of said inlets, means retainingsaid valve in closed position in said one of said inlets whenever said pumping unit is positioned uprightly during normal flight conditions, and position sensitive means rendering said last mentioned -rrie'an's inoperative whenever said pumping unit is tilted towards inverted position during abnormal flight conditions to open said poppet valve. I 7

10. A pump unit comprising an electric motor, a centrifugal pump casing on each end of the motor, an impeller in each casing coupled to the motor, said casings having separate central suction inlets and separate peripheral outlets, a conduit connecting said outlets, means for mounting the unit in an upright position to place the inlets at different levels, a pressure sensitive valve closing the inlet of the top pump casing, means exerting a bias against said pressuresensiave valve in a valve opening direction, means defining a passage connected to said conduit and said valve and bleeding pump discharge pressure to the pressure sensitive valve for closing the pressure sensitive valve in normal flight when the discharge pressure exerts a pressure force exceasing the biasing force, and a gravity sensitive vent in the bleeder passage means selectivelyrelievi'ng pressure in said passage to a value less w en P e l .w je r n asterisk means open the pressure sensitive "valve only when the unitis inverted or subjected, to negative gravity conditions as in abnormal flight,

11. A pump unit comprising amotor, a centrifugal'p'ump casing oneach end of the motor, an impeller in each casing 'coupled to the motor, said casing having separatesuction inlets arranged at different levels and separate outlets, adi'scharge conduit connecting both of said out lets, means for maintaining the pumpunit in an upright position with the pump casings vertically spaced a lig nmenaan inlet valvein the inlet of the upper pump, a pressure control chamber in the upper casing behind said inlet valve and operably associated therewith to impart pressure forces thereto, a passageway between the pressure control chamber and said discharge conduit, said inlet valve being closed said pressure forces upon a build-up of pressure in saidcontrol chamber, a gravity responsive check valve in the upper casing to referenc'e said control chamber to a point at lower pressure, said gravity responsive check valve operative to reduce the pressure in said control chamber whenever said pump unit is tilted out of an upright position and control biasing means tending to bias said inlet valve open, whereby said upper inlet will be normallvclosed whenever'sa'idpump unit is positioned uprightly and will be opened whenever said pump unit is tilted away from upright position. i r I 12. A pumping unit comprising a motor, a centrifugal pump on each end of said motor, each pump having separate suction inlets spac ed apart irom one another, said pumps having "a common discharge outlet, means mounting said pumpin unit in no'rmally upright position with said separate suction inlets arranged in vertically spaced alignment, an inlet valve in the inlet of the uppermost pump, means iormin'g a pressure control chamber behind said inlet valve and in operable relation thereto to eker't pressure forces thereon, means forming a passageway irom said pressure control chamber to said common discharge outlet, ares'triction insaid passageway to control the flow of discharged fluid therethrough and a gravity responsive check valve referencing said control chamber to a point at lower pressure, said inlet valve normally ur ed closed by discharge pressure forces developed in said control chamber whenever said pumping unit is positioned uprightly, said inlet valve arranged to open when said pumping unit is tilted away from uprightposition and said gravity responsive check 'valve is actuated to reduce the pressure in said control chamben t V 13. A pumping unit comprising a mans centrifugal pump on each end of said motor, each pump having separate suction inlets spaced apart from one another, said pumps having a common discharge outlet, means mounting said pumping unit in normally upright position with said separate suction inlets arranged in vertically sDa-Ced ali nment, an inlet valve in the inlet of the uppermost pump, means forminga pressure control chamber behind said in let valve and in operable relation therewith to impart pressure forces thereto, means forming a passageway from said pressure control chamber to said common discharge outlet, a restriction in said passageway to control the flow of discharged fluid therethrough and a gravity responsive check valve referencing said control chamber to a point at lower pressure, said inlet valve normally urged closed by discharge pressure forces developed in said control chamber whenever said pumping unit is positioned uprightly, said inlet valve arranged to open when said pumping unit is tilted away from upright position and said gravity responsive check valve is actuated to reduce the pressure in said control chamber, said inlet valve further including a control biasing means normally urging said inlet valve open to assist in opening said inlet valve whenever the pressure in said control chamber is reduced below a predetermined value.

FREDERICK E. SMITH.

References Cited in the file of this patent UNITED STATES PATENTS Number 5 1,933,753 2,016,278 2,546,034 2,547,246 

